xref: /openbmc/linux/lib/string.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  *  linux/lib/string.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6 
7 /*
8  * stupid library routines.. The optimized versions should generally be found
9  * as inline code in <asm-xx/string.h>
10  *
11  * These are buggy as well..
12  *
13  * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
14  * -  Added strsep() which will replace strtok() soon (because strsep() is
15  *    reentrant and should be faster). Use only strsep() in new code, please.
16  *
17  * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
18  *                    Matthew Hawkins <matt@mh.dropbear.id.au>
19  * -  Kissed strtok() goodbye
20  */
21 
22 #include <linux/types.h>
23 #include <linux/string.h>
24 #include <linux/ctype.h>
25 #include <linux/module.h>
26 
27 #ifndef __HAVE_ARCH_STRNICMP
28 /**
29  * strnicmp - Case insensitive, length-limited string comparison
30  * @s1: One string
31  * @s2: The other string
32  * @len: the maximum number of characters to compare
33  */
34 int strnicmp(const char *s1, const char *s2, size_t len)
35 {
36 	/* Yes, Virginia, it had better be unsigned */
37 	unsigned char c1, c2;
38 
39 	c1 = c2 = 0;
40 	if (len) {
41 		do {
42 			c1 = *s1;
43 			c2 = *s2;
44 			s1++;
45 			s2++;
46 			if (!c1)
47 				break;
48 			if (!c2)
49 				break;
50 			if (c1 == c2)
51 				continue;
52 			c1 = tolower(c1);
53 			c2 = tolower(c2);
54 			if (c1 != c2)
55 				break;
56 		} while (--len);
57 	}
58 	return (int)c1 - (int)c2;
59 }
60 EXPORT_SYMBOL(strnicmp);
61 #endif
62 
63 #ifndef __HAVE_ARCH_STRCPY
64 /**
65  * strcpy - Copy a %NUL terminated string
66  * @dest: Where to copy the string to
67  * @src: Where to copy the string from
68  */
69 #undef strcpy
70 char *strcpy(char *dest, const char *src)
71 {
72 	char *tmp = dest;
73 
74 	while ((*dest++ = *src++) != '\0')
75 		/* nothing */;
76 	return tmp;
77 }
78 EXPORT_SYMBOL(strcpy);
79 #endif
80 
81 #ifndef __HAVE_ARCH_STRNCPY
82 /**
83  * strncpy - Copy a length-limited, %NUL-terminated string
84  * @dest: Where to copy the string to
85  * @src: Where to copy the string from
86  * @count: The maximum number of bytes to copy
87  *
88  * The result is not %NUL-terminated if the source exceeds
89  * @count bytes.
90  *
91  * In the case where the length of @src is less than  that  of
92  * count, the remainder of @dest will be padded with %NUL.
93  *
94  */
95 char *strncpy(char *dest, const char *src, size_t count)
96 {
97 	char *tmp = dest;
98 
99 	while (count) {
100 		if ((*tmp = *src) != 0)
101 			src++;
102 		tmp++;
103 		count--;
104 	}
105 	return dest;
106 }
107 EXPORT_SYMBOL(strncpy);
108 #endif
109 
110 #ifndef __HAVE_ARCH_STRLCPY
111 /**
112  * strlcpy - Copy a %NUL terminated string into a sized buffer
113  * @dest: Where to copy the string to
114  * @src: Where to copy the string from
115  * @size: size of destination buffer
116  *
117  * Compatible with *BSD: the result is always a valid
118  * NUL-terminated string that fits in the buffer (unless,
119  * of course, the buffer size is zero). It does not pad
120  * out the result like strncpy() does.
121  */
122 size_t strlcpy(char *dest, const char *src, size_t size)
123 {
124 	size_t ret = strlen(src);
125 
126 	if (size) {
127 		size_t len = (ret >= size) ? size - 1 : ret;
128 		memcpy(dest, src, len);
129 		dest[len] = '\0';
130 	}
131 	return ret;
132 }
133 EXPORT_SYMBOL(strlcpy);
134 #endif
135 
136 #ifndef __HAVE_ARCH_STRCAT
137 /**
138  * strcat - Append one %NUL-terminated string to another
139  * @dest: The string to be appended to
140  * @src: The string to append to it
141  */
142 #undef strcat
143 char *strcat(char *dest, const char *src)
144 {
145 	char *tmp = dest;
146 
147 	while (*dest)
148 		dest++;
149 	while ((*dest++ = *src++) != '\0')
150 		;
151 	return tmp;
152 }
153 EXPORT_SYMBOL(strcat);
154 #endif
155 
156 #ifndef __HAVE_ARCH_STRNCAT
157 /**
158  * strncat - Append a length-limited, %NUL-terminated string to another
159  * @dest: The string to be appended to
160  * @src: The string to append to it
161  * @count: The maximum numbers of bytes to copy
162  *
163  * Note that in contrast to strncpy, strncat ensures the result is
164  * terminated.
165  */
166 char *strncat(char *dest, const char *src, size_t count)
167 {
168 	char *tmp = dest;
169 
170 	if (count) {
171 		while (*dest)
172 			dest++;
173 		while ((*dest++ = *src++) != 0) {
174 			if (--count == 0) {
175 				*dest = '\0';
176 				break;
177 			}
178 		}
179 	}
180 	return tmp;
181 }
182 EXPORT_SYMBOL(strncat);
183 #endif
184 
185 #ifndef __HAVE_ARCH_STRLCAT
186 /**
187  * strlcat - Append a length-limited, %NUL-terminated string to another
188  * @dest: The string to be appended to
189  * @src: The string to append to it
190  * @count: The size of the destination buffer.
191  */
192 size_t strlcat(char *dest, const char *src, size_t count)
193 {
194 	size_t dsize = strlen(dest);
195 	size_t len = strlen(src);
196 	size_t res = dsize + len;
197 
198 	/* This would be a bug */
199 	BUG_ON(dsize >= count);
200 
201 	dest += dsize;
202 	count -= dsize;
203 	if (len >= count)
204 		len = count-1;
205 	memcpy(dest, src, len);
206 	dest[len] = 0;
207 	return res;
208 }
209 EXPORT_SYMBOL(strlcat);
210 #endif
211 
212 #ifndef __HAVE_ARCH_STRCMP
213 /**
214  * strcmp - Compare two strings
215  * @cs: One string
216  * @ct: Another string
217  */
218 #undef strcmp
219 int strcmp(const char *cs, const char *ct)
220 {
221 	signed char __res;
222 
223 	while (1) {
224 		if ((__res = *cs - *ct++) != 0 || !*cs++)
225 			break;
226 	}
227 	return __res;
228 }
229 EXPORT_SYMBOL(strcmp);
230 #endif
231 
232 #ifndef __HAVE_ARCH_STRNCMP
233 /**
234  * strncmp - Compare two length-limited strings
235  * @cs: One string
236  * @ct: Another string
237  * @count: The maximum number of bytes to compare
238  */
239 int strncmp(const char *cs, const char *ct, size_t count)
240 {
241 	signed char __res = 0;
242 
243 	while (count) {
244 		if ((__res = *cs - *ct++) != 0 || !*cs++)
245 			break;
246 		count--;
247 	}
248 	return __res;
249 }
250 EXPORT_SYMBOL(strncmp);
251 #endif
252 
253 #ifndef __HAVE_ARCH_STRCHR
254 /**
255  * strchr - Find the first occurrence of a character in a string
256  * @s: The string to be searched
257  * @c: The character to search for
258  */
259 char *strchr(const char *s, int c)
260 {
261 	for (; *s != (char)c; ++s)
262 		if (*s == '\0')
263 			return NULL;
264 	return (char *)s;
265 }
266 EXPORT_SYMBOL(strchr);
267 #endif
268 
269 #ifndef __HAVE_ARCH_STRRCHR
270 /**
271  * strrchr - Find the last occurrence of a character in a string
272  * @s: The string to be searched
273  * @c: The character to search for
274  */
275 char *strrchr(const char *s, int c)
276 {
277        const char *p = s + strlen(s);
278        do {
279            if (*p == (char)c)
280                return (char *)p;
281        } while (--p >= s);
282        return NULL;
283 }
284 EXPORT_SYMBOL(strrchr);
285 #endif
286 
287 #ifndef __HAVE_ARCH_STRNCHR
288 /**
289  * strnchr - Find a character in a length limited string
290  * @s: The string to be searched
291  * @count: The number of characters to be searched
292  * @c: The character to search for
293  */
294 char *strnchr(const char *s, size_t count, int c)
295 {
296 	for (; count-- && *s != '\0'; ++s)
297 		if (*s == (char)c)
298 			return (char *)s;
299 	return NULL;
300 }
301 EXPORT_SYMBOL(strnchr);
302 #endif
303 
304 #ifndef __HAVE_ARCH_STRLEN
305 /**
306  * strlen - Find the length of a string
307  * @s: The string to be sized
308  */
309 size_t strlen(const char *s)
310 {
311 	const char *sc;
312 
313 	for (sc = s; *sc != '\0'; ++sc)
314 		/* nothing */;
315 	return sc - s;
316 }
317 EXPORT_SYMBOL(strlen);
318 #endif
319 
320 #ifndef __HAVE_ARCH_STRNLEN
321 /**
322  * strnlen - Find the length of a length-limited string
323  * @s: The string to be sized
324  * @count: The maximum number of bytes to search
325  */
326 size_t strnlen(const char *s, size_t count)
327 {
328 	const char *sc;
329 
330 	for (sc = s; count-- && *sc != '\0'; ++sc)
331 		/* nothing */;
332 	return sc - s;
333 }
334 EXPORT_SYMBOL(strnlen);
335 #endif
336 
337 #ifndef __HAVE_ARCH_STRSPN
338 /**
339  * strspn - Calculate the length of the initial substring of @s which only
340  * 	contain letters in @accept
341  * @s: The string to be searched
342  * @accept: The string to search for
343  */
344 size_t strspn(const char *s, const char *accept)
345 {
346 	const char *p;
347 	const char *a;
348 	size_t count = 0;
349 
350 	for (p = s; *p != '\0'; ++p) {
351 		for (a = accept; *a != '\0'; ++a) {
352 			if (*p == *a)
353 				break;
354 		}
355 		if (*a == '\0')
356 			return count;
357 		++count;
358 	}
359 	return count;
360 }
361 
362 EXPORT_SYMBOL(strspn);
363 #endif
364 
365 /**
366  * strcspn - Calculate the length of the initial substring of @s which does
367  * 	not contain letters in @reject
368  * @s: The string to be searched
369  * @reject: The string to avoid
370  */
371 size_t strcspn(const char *s, const char *reject)
372 {
373 	const char *p;
374 	const char *r;
375 	size_t count = 0;
376 
377 	for (p = s; *p != '\0'; ++p) {
378 		for (r = reject; *r != '\0'; ++r) {
379 			if (*p == *r)
380 				return count;
381 		}
382 		++count;
383 	}
384 	return count;
385 }
386 EXPORT_SYMBOL(strcspn);
387 
388 #ifndef __HAVE_ARCH_STRPBRK
389 /**
390  * strpbrk - Find the first occurrence of a set of characters
391  * @cs: The string to be searched
392  * @ct: The characters to search for
393  */
394 char *strpbrk(const char *cs, const char *ct)
395 {
396 	const char *sc1, *sc2;
397 
398 	for (sc1 = cs; *sc1 != '\0'; ++sc1) {
399 		for (sc2 = ct; *sc2 != '\0'; ++sc2) {
400 			if (*sc1 == *sc2)
401 				return (char *)sc1;
402 		}
403 	}
404 	return NULL;
405 }
406 EXPORT_SYMBOL(strpbrk);
407 #endif
408 
409 #ifndef __HAVE_ARCH_STRSEP
410 /**
411  * strsep - Split a string into tokens
412  * @s: The string to be searched
413  * @ct: The characters to search for
414  *
415  * strsep() updates @s to point after the token, ready for the next call.
416  *
417  * It returns empty tokens, too, behaving exactly like the libc function
418  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
419  * Same semantics, slimmer shape. ;)
420  */
421 char *strsep(char **s, const char *ct)
422 {
423 	char *sbegin = *s;
424 	char *end;
425 
426 	if (sbegin == NULL)
427 		return NULL;
428 
429 	end = strpbrk(sbegin, ct);
430 	if (end)
431 		*end++ = '\0';
432 	*s = end;
433 	return sbegin;
434 }
435 EXPORT_SYMBOL(strsep);
436 #endif
437 
438 #ifndef __HAVE_ARCH_MEMSET
439 /**
440  * memset - Fill a region of memory with the given value
441  * @s: Pointer to the start of the area.
442  * @c: The byte to fill the area with
443  * @count: The size of the area.
444  *
445  * Do not use memset() to access IO space, use memset_io() instead.
446  */
447 void *memset(void *s, int c, size_t count)
448 {
449 	char *xs = s;
450 
451 	while (count--)
452 		*xs++ = c;
453 	return s;
454 }
455 EXPORT_SYMBOL(memset);
456 #endif
457 
458 #ifndef __HAVE_ARCH_MEMCPY
459 /**
460  * memcpy - Copy one area of memory to another
461  * @dest: Where to copy to
462  * @src: Where to copy from
463  * @count: The size of the area.
464  *
465  * You should not use this function to access IO space, use memcpy_toio()
466  * or memcpy_fromio() instead.
467  */
468 void *memcpy(void *dest, const void *src, size_t count)
469 {
470 	char *tmp = dest;
471 	char *s = src;
472 
473 	while (count--)
474 		*tmp++ = *s++;
475 	return dest;
476 }
477 EXPORT_SYMBOL(memcpy);
478 #endif
479 
480 #ifndef __HAVE_ARCH_MEMMOVE
481 /**
482  * memmove - Copy one area of memory to another
483  * @dest: Where to copy to
484  * @src: Where to copy from
485  * @count: The size of the area.
486  *
487  * Unlike memcpy(), memmove() copes with overlapping areas.
488  */
489 void *memmove(void *dest, const void *src, size_t count)
490 {
491 	char *tmp;
492 	const char *s;
493 
494 	if (dest <= src) {
495 		tmp = dest;
496 		s = src;
497 		while (count--)
498 			*tmp++ = *s++;
499 	} else {
500 		tmp = dest;
501 		tmp += count;
502 		s = src;
503 		s += count;
504 		while (count--)
505 			*--tmp = *--s;
506 	}
507 	return dest;
508 }
509 EXPORT_SYMBOL(memmove);
510 #endif
511 
512 #ifndef __HAVE_ARCH_MEMCMP
513 /**
514  * memcmp - Compare two areas of memory
515  * @cs: One area of memory
516  * @ct: Another area of memory
517  * @count: The size of the area.
518  */
519 #undef memcmp
520 int memcmp(const void *cs, const void *ct, size_t count)
521 {
522 	const unsigned char *su1, *su2;
523 	int res = 0;
524 
525 	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
526 		if ((res = *su1 - *su2) != 0)
527 			break;
528 	return res;
529 }
530 EXPORT_SYMBOL(memcmp);
531 #endif
532 
533 #ifndef __HAVE_ARCH_MEMSCAN
534 /**
535  * memscan - Find a character in an area of memory.
536  * @addr: The memory area
537  * @c: The byte to search for
538  * @size: The size of the area.
539  *
540  * returns the address of the first occurrence of @c, or 1 byte past
541  * the area if @c is not found
542  */
543 void *memscan(void *addr, int c, size_t size)
544 {
545 	unsigned char *p = addr;
546 
547 	while (size) {
548 		if (*p == c)
549 			return (void *)p;
550 		p++;
551 		size--;
552 	}
553   	return (void *)p;
554 }
555 EXPORT_SYMBOL(memscan);
556 #endif
557 
558 #ifndef __HAVE_ARCH_STRSTR
559 /**
560  * strstr - Find the first substring in a %NUL terminated string
561  * @s1: The string to be searched
562  * @s2: The string to search for
563  */
564 char *strstr(const char *s1, const char *s2)
565 {
566 	int l1, l2;
567 
568 	l2 = strlen(s2);
569 	if (!l2)
570 		return (char *)s1;
571 	l1 = strlen(s1);
572 	while (l1 >= l2) {
573 		l1--;
574 		if (!memcmp(s1, s2, l2))
575 			return (char *)s1;
576 		s1++;
577 	}
578 	return NULL;
579 }
580 EXPORT_SYMBOL(strstr);
581 #endif
582 
583 #ifndef __HAVE_ARCH_MEMCHR
584 /**
585  * memchr - Find a character in an area of memory.
586  * @s: The memory area
587  * @c: The byte to search for
588  * @n: The size of the area.
589  *
590  * returns the address of the first occurrence of @c, or %NULL
591  * if @c is not found
592  */
593 void *memchr(const void *s, int c, size_t n)
594 {
595 	const unsigned char *p = s;
596 	while (n-- != 0) {
597         	if ((unsigned char)c == *p++) {
598 			return (void *)(p - 1);
599 		}
600 	}
601 	return NULL;
602 }
603 EXPORT_SYMBOL(memchr);
604 #endif
605